Percutaneous catheter ablation is a well-established technique for treating cardiac arrhythmia by targeting tissue at the site of the abnormal electrical activity. Various forms of ablative energy may be delivered via a transvenous catheter. The most common transvenous catheters are radiofrequency (RF) ablation and cryotherapy. Atrial fibrillation (AF), the most frequently occurring supraventricular tachyarrhythmia, may be initiated by ectopic heart beats that originate in or around the ostia of the pulmonary veins. The isolation of pulmonary veins (referred to as pulmonary vein isolation, or PVI) has been demonstrated to be the cornerstone of paroxysmal AF treatment.
Literature suggests that other structures or sites may participate in triggering or sustaining AF. Electrogram-guided ablation of complex atrial fractionated electrograms (CAFEs), ganglionated plexi (GPs), and other sites and structures (substrate modification) can be considered as target sites for targeting treatment for terminating AF.
A number of devices have been proposed that provide ablation and mapping capabilities so that a single device may be used to not only detect sites that support AF, but also may be used to treat such sites and terminate AF using electrogram-guided ablation. However, these devices have several drawbacks. First, a versatile catheter is desired that can provide not only wide-area ablation, but that can also create focal and/or circular lesions. However, these devices do not provide electrogram (EGM) sensing capabilities on the ablation element. Therefore, the treatment area of the device must be manipulated within the patient between a mapping configuration and an ablation configuration, which complicates the treatment procedure. Second, combining functionalities such as mapping and cryoablation into a multi-function catheter may increase the likelihood that leaks develop and gas egress into the heart occurs. Third, the integration of multiple functionalities into a single device significantly increases the cost and complexity of its fabrication and can result in a device that is larger than is optimal in order to accommodate the device components within. This increase in size can make navigation of the device within the patient difficult and is also more likely to injure the patient.
It is therefore desirable to provide a multi-function catheter that is capable of both mapping and treating tissue. It is further desirable to provide a multi-functionality device that is capable of creating a variety of ablation patterns, such as wide-area, focal, and circular ablation patterns, and that does not necessitate the inclusion of an increased amount of device and/or system components over those required for an ablation device alone.